Step | Hyp | Ref
| Expression |
1 | | elex 3459 |
. 2
⊢ (𝐴 ∈ (𝐵 ∩ 𝐶) → 𝐴 ∈ V) |
2 | | elex 3459 |
. . 3
⊢ (𝐴 ∈ 𝐶 → 𝐴 ∈ V) |
3 | 2 | adantl 485 |
. 2
⊢ ((𝐴 ∈ 𝐵 ∧ 𝐴 ∈ 𝐶) → 𝐴 ∈ V) |
4 | | eleq1 2877 |
. . . 4
⊢ (𝑥 = 𝑦 → (𝑥 ∈ 𝐵 ↔ 𝑦 ∈ 𝐵)) |
5 | | eleq1 2877 |
. . . 4
⊢ (𝑥 = 𝑦 → (𝑥 ∈ 𝐶 ↔ 𝑦 ∈ 𝐶)) |
6 | 4, 5 | anbi12d 633 |
. . 3
⊢ (𝑥 = 𝑦 → ((𝑥 ∈ 𝐵 ∧ 𝑥 ∈ 𝐶) ↔ (𝑦 ∈ 𝐵 ∧ 𝑦 ∈ 𝐶))) |
7 | | eleq1 2877 |
. . . 4
⊢ (𝑦 = 𝐴 → (𝑦 ∈ 𝐵 ↔ 𝐴 ∈ 𝐵)) |
8 | | eleq1 2877 |
. . . 4
⊢ (𝑦 = 𝐴 → (𝑦 ∈ 𝐶 ↔ 𝐴 ∈ 𝐶)) |
9 | 7, 8 | anbi12d 633 |
. . 3
⊢ (𝑦 = 𝐴 → ((𝑦 ∈ 𝐵 ∧ 𝑦 ∈ 𝐶) ↔ (𝐴 ∈ 𝐵 ∧ 𝐴 ∈ 𝐶))) |
10 | | df-in 3888 |
. . 3
⊢ (𝐵 ∩ 𝐶) = {𝑥 ∣ (𝑥 ∈ 𝐵 ∧ 𝑥 ∈ 𝐶)} |
11 | 6, 9, 10 | elab2gw 3613 |
. 2
⊢ (𝐴 ∈ V → (𝐴 ∈ (𝐵 ∩ 𝐶) ↔ (𝐴 ∈ 𝐵 ∧ 𝐴 ∈ 𝐶))) |
12 | 1, 3, 11 | pm5.21nii 383 |
1
⊢ (𝐴 ∈ (𝐵 ∩ 𝐶) ↔ (𝐴 ∈ 𝐵 ∧ 𝐴 ∈ 𝐶)) |